1. Field of the Invention
The invention relates to a winding device for winding a web-shaped material, and a method of changing a reel in a winding device .
2. Description of Related Art
Winding devices conforming to their genre comprise a reel for receiving the web-shaped material. This material is fed over a contact roller to the current reel and is pressed against the reel. Often the contact roller is rotatable, but is otherwise mounted on the machine frame of the winding device in such a way that said contact roller is stationary.
When the current reel is completely wound, a new reel has to be available for the next phase of the winding process. The new, still empty reel is advanced to the web-shaped material. Since the web shaped material and the still empty reel attract each other no later than upon direct contact (for this purpose there is, for example, a double-sided adhesive tape on the still empty reel; or an electrostatic charging is used for this purpose), the web-shaped material has to be severed at the appropriate moment. Generally this so-called pre-winding process occurs while the still empty reel is engaged at the contact roller or shortly after the still empty reel was engaged at the contact roller.
In this context a still empty reel consists of a reel shaft and usually a reel core, which has been slid onto the reel shaft. The reel core forms together with the wound material the core. In principle, it is also possible to wind without a reel core.
In this case a still empty reel is often stored in a reel magazine. When the reel is to be changed, an empty reel is removed from the magazine and conveyed to the contact roller by means of a device for feeding the still empty reel to the contact roller until said empty reel touches the contact roller. At that moment the reel is taken by a retaining device and usually connected to a reel drive, so that the reel, which at this point has already taken up the web-shaped material, can rotate at its own defined circumferential speed. However, it is also possible to let the reel be driven solely by the contact roller.
In order to be able to carry out a reel change in the correct way and in order to obtain in the end a winding of high quality, the still empty reel is driven in rotation. In this case said empty reel is often speeded up until its circumferential speed is equal to more or less the circumferential speed of the contact roller.
In actually existing winding devices of the applicant the rotary drive of the still empty reel is effected by a driven gear that is mounted on the periphery of the reel, usually in the region of its pin. If however, the still empty reel is fed to the contact roller, then this contact is released and the reel shaft rotates freely. If at this point this feeding takes a relatively long time, then the rotational motion of the reel has often slowed down, so that its circumferential speed is often significantly less than the circumferential speed of the contact roller. As a result, the conditions for proper pre-winding are often no longer met.
Therefore, the object of the present invention is to further develop the known winding device in such a way that these disadvantages are avoided.